The presence of metal parts on the exterior of mobile devices is becoming increasingly prevalent for reasons of aesthetics and mechanical sturdiness. 4G mobile devices are required to operate over the GSM850/900/1800/1900 UMTS bands (824-896/880-960/1710-1880/1850-1990/1920-2170 MHz) as well as the LTE700/2300/2500 bands (698-787/2305-2400/2500-2690 MHz), which can be grouped as follows: low band (698-960 MHz), middle band (1710-2170 MHz), and high band (2300-2690 MHz). Further, the LTE Advanced standard requires carrier aggregation, i.e., two carriers that may be non-contiguous being aggregated to increase the data rate. The requirements for tri-band operation and accommodating carrier aggregation give rise to challenges in fitting antennas into a compact phone design with multi-operating frequencies, and good diversity and capacity performance.